Blew up half the chemistry lab with my friends, accidentally dropped some concentrated H2SO4 on a hot girl's shoes in the same lab (made things really awkward, that did), used my chem skills to secretly make some chloroform while our teacher wasn't looking, dripped ethanol on the wall in the form of words and set it on fire so they could see some flaming words on the wall (which said some really rude stuff).
Also aided the guys in my class in setting some firecrackers off.
Also, there was a massive softboard in the staff room detailing their schedule for meetings, classes etc. I sneaked in and changed as many of the timings I could.
Oh, and we had this dude back in the 10th grade who tried to bully me because he thought I was a "nerd". Had a massive fight with him in front of the entire grade in which I shattered his nose and almost broke his left arm. The next week he came to school with a heavily bandaged face and a sling for his arm. That was GLORIOUS
So much for being a "nerd".
Er....what else? Oh yeah, I used to have a very explosive temper as a small child. My first day EVER of school (except the school I was in at age 4-5) had the teacher introduce me to the other kids, who then told us all that she's going outside for a bit to talk to someone. I was sitting again next to the same dude whose nose I broke in the 10th grade, who said, "Hi, my name's....", and while doing so he took my brand new shiny Spider-man pencil box and chucked it out the window.
My Spider-man pencil box. MY SPIDER-MAN PENCIL BOX. I loved that pencil box.
As exploding with anger as a 6 year old kid can be, I faced him and snatched his entire school bag, with his books and pencil box and food and bottle and everything and threw it outside.
So, yeah. I've done some stuff. But I do extremely well in school so I almost, always get off more or less free. I've always used this to my advantage in getting out of bad spots. The teachers never can associate any of the disasters directly or indirectly caused by me to that nice, polite guy always in perfect uniform they see walking the corridors.